Hey all, 7 times to the dealer on my 09 JK standard tranny. The throttle was sticking and rpms extrememly slow on the decline. They replaced the mapping sensor fixing the sticky throttle, but tell me that JK Jeeps are designed to have a slow RPM decline (which I can't buy is truth). At 36,000 miles, the clutch is getting prematuraly worn and shifting from 1st to 2nd is getting more rigid. Not to mention that 4x'ing is frustrating when the engine isn't where you need it to be.

Any thoughts? Anyone else have or heard of this issue? Thanks!

 

Welcome to the club of problems.Some of us have them,some of us don't.

 

Have you tried cleaning the throttle body? And how fast do you expect the rpms to drop?

 

My rpm drop fairly slow and sometimes they hang up obnoxiously.

Side note: I had an '09 Civic Si that had an annoying rev hang issue which turned out to be programmed into the engine for improved emissions. Something about not burning all the fuel if it dropped immediately. Dumb.

 

The simple joys of owning a vehicle with drive by wire technology.....I would much rather have the cable from my gas pedal to my throttle body back.

 

I had an '09 with the 3.8 as well, manual trans.

I do remember the engine being really slow to spin down in normal driving between shifts. It was consistent in its latency, so I attributed it to having a really heavy flywheel, which is probably accurate given the 3.8's design. Unrelated, but I know the feeling well from driving little British cars. A lot of them have motors carried over from farm equipment, for example, Triumph used some 4-cylinder engines that were identical to the ones used in some popular tractor models at the time.

In the Jeep, I remember I had to teach myself to shift extra slow....clutch in, shift, wait for RPM's to drop, let clutch out. It's a truck, not a sports car, and the shift throws are ridiculously long, too.

The other feature (curse) I think is the drive-by-wire system. I noticed what could almost be described as an RPM hold at freeway speeds on decel, most noticably at high rpm's coming over mountain passes, etc. It stops if you blip the throttle ever so slightly as if to tell the engine "no, I'm still here...and I'm driving, not you..."

 

If it's something that gets in the way of normal driving, then there is a problem such as a dirty throttle body, etc.

There is a delay programmed in, to slow throttle closing for emission reasons, and maybe even leave it open a little during deceleration.

It's nothing new, and not just on throttle-by-wire engines.
They started doing this when emissions came to the forefront, back in the carburetor days.
I remember seeing a dash-pot on the carburetor's throttle arm to slow the closing of the butterfly. (It was a cable throttle system.)
Lots of people would adjust the dash-pot, or remove it completely.

 

Lol... I've got them all except this ome thank gooodnes.

 

I just had my 09 JKU out on a sandtrack out in the desert today and experieced a throttle issue while driving in 4H, Drive at ~ 80km/hr. From time to time, while keeping the accelerator pedal at the same position, the RPM's would just start dropping and the vehicle would decelerate as if it were dying. At cruise speed I'm doing about 2200 RPM, then all of a sudden the RPM's start dropping down below 1500 and it feels like the vehicle is dying, but I didn't move the pedal position. So I put the pedal to the floor and then it rapidly jumps up over 3000 RPMs so I let off a bit and I'm back around 2200 again. It started happening more frequently as the day went on. Then I got on the highway back in 2WD and no problems for the remaining couple hundred clicks home.

I'm suspecting that maybe I need a reprogram of my Throttle Position Sensor, but I don't really have a freakin' clue. What do you more knowledgeable folks think?